JP7273088B2 - Antimony-containing materials for ion implantation - Google Patents

Description

The present invention relates to novel antimony-containing materials for ion implantation and conditions suitable for storage and delivery of materials for ion implantation processes.

Ion implantation is an important process in semiconductor/microelectronic manufacturing. Ion implantation processes are typically used in the manufacture of integrated circuits to introduce dopant impurities into semiconductor wafers. Generally speaking, for semiconductor applications, ion implantation is the use of dopant gases, commonly referred to as dopant impurities, to alter the physical, chemical and/or electrical properties of the wafer in a desired manner. , with the introduction of ions into the semiconductor wafer. Desired dopant impurities are introduced into the semiconductor wafer in trace amounts to form doped regions at desired depths into the surface of the wafer. The dopant impurity is selected to combine with the semiconductor wafer to generate electrical carriers, thereby changing the conductivity of the semiconductor wafer. The concentration or dose of dopant impurities introduced into the wafer determines the conductivity of the doped regions. In this manner, several impurity regions are formed to form transistor structures, isolation structures, and other electronic structures that collectively function as semiconductor devices.

An ion source is used to generate an ion beam of ion species from a source dopant gas. An ion source is an important component of an ion implantation system, and serves to ionize dopant gases to produce the specific dopant ions that are implanted during the implantation process. The ion source chamber includes a cathode, such as a filament made of tungsten (W) or a tungsten alloy, which is heated to its thermionic generation temperature to generate electrons. The electrons accelerate toward the arc chamber wall and collide with dopant source gas molecules within the arc chamber to generate a plasma. The plasma contains dissociated ions of dopant gas species, radicals, and neutral atoms and molecules. Ion species are extracted from the arc chamber and then separated from other ion species based on mass. Only ions in the beam based on a particular mass-to-charge ratio are allowed to pass through the filter. The selected mass of ions contains the desired ion species, which are then directed to the target substrate and implanted into the target substrate at the required depth and dose.

Current semiconductor device technology utilizes various dopant species in specific amounts to produce p-type and n-type semiconductors, both of which are used in the fabrication of transistor and diode electronic devices. considered an element. The difference between p-type and n-type dopants is primarily related to the charge-carrying species introduced into the semiconductor crystal lattice. Because p-type dopants generate electron "holes" in the semiconductor material by creating electron vacancies in the valence band, while n-type dopants are used to generate free electrons in the semiconductor material. used for Antimony (Sb) is one example of a commonly used dopant species required in today's electronic devices. Sb is an n-type dopant with many desirable applications that continue to attract interest in the semiconductor industry. For example, indium antimonide is a narrow bandgap III-V semiconductor used as an infrared detector. Antimony also provides ultra-shallow pn junctions in finFET devices, channel threshold voltage adjustment in MOSFETs, punch-through stop halo implants in pMOS devices, and source-drain regions in germanium n-MOSFETs. used to form.

Currently, solid sources of Sb are used as dopant materials. Elemental Sb metal can be used for ion implantation by positioning it in close proximity to the filament. During ion implantation, the temperature of the filament is sufficiently high that radiative heating causes Sb to evaporate and collide with electrons to produce Sb-containing ions for doping. However, this method may deposit Sb on the chamber walls or on the filament, shortening the life of the filament. Solid compounds of Sb are also used as dopant sources such as SbF ₃ , SbCl ₃ and Sb ₂ O ₃ , but these compounds require It should be heated to above 160°C. Additionally, all flow lines in the system are typically heated to prevent re-condensation of the solid source of Sb prior to reaching the arc chamber.

In view of the operational challenges of solid sources of Sb for implanting Sb-containing ions, gaseous sources of Sb have been considered. In particular, _SbH3 and _SbD3 have been proposed as gaseous sources of Sb, but these compounds are unstable and decomposing at room temperature.

There are no currently viable Sb dopant sources available for ion implantation today. There is an unmet need for a reliable Sb dopant source that can be used in conventional ion implantation systems.

The invention may include any of the following aspects in various combinations, and may include any other aspects described below in the written description or accompanying drawings.

The present invention relates, in part, to methods and systems for using antimony dopant compositions. It has been found that the composition of Sb-containing material utilized herein improves the ease of delivery to an ion implantation process and substantially reduces the build-up of Sb-containing deposits within the ion chamber. It is

In a first aspect, a composition suitable for ion implantation for implanting antimony-containing ions to produce an n-type electronic device structure, comprising an antimony-containing material, the antimony material being exposed to ambient temperature containing an antimony-containing material that is chemically stable under sub-atmospheric pressure and is maintained under liquid phase storage conditions, further characterized by the lack of traces of moisture; The antimony-containing material is represented by a non-carbon-containing chemical formula, wherein the antimony-containing material is in substantial equilibrium with a corresponding gas phase adapted to exert sufficient vapor pressure in response to downstream vacuum pressure conditions. It is in liquid phase.

In a second aspect, a sub-atmospheric storage and delivery container for a composition suitable for ion implantation to implant antimony ions to produce an n-type electronic device structure, the antimony-containing material comprising: The antimony-containing material comprises an antimony-containing material that is chemically stable at ambient temperature, the antimony-containing material being represented by a non-carbon-containing chemical formula and characterized by the absence of traces of moisture. A storage and delivery vessel at least partially defined by the environment, the storage and delivery vessel configured to hold the antimony-containing material in a liquid phase under sub-atmospheric conditions, whereby the liquid A phase comprises a storage and delivery container that is in substantial equilibrium with a corresponding gas phase that occupies the headspace of the storage and delivery container.

In a third aspect, a method of operating an ion source for implanting Sb-containing ions, comprising introducing a vapor phase antimony-containing material into an arc chamber at a flow rate of at least about 0.1 sccm or greater; ionizing the composition to produce Sb-containing ions in the arc chamber; and implanting the Sb-containing ions into the substrate.

In a fourth aspect, an adsorbent comprising a deliverable adsorption capacity for subatmospheric storage and delivery for a composition suitable for ion implantation to implant antimony ions to produce an n-type electronic device structure. wherein the composition comprises an antimony-containing material, the antimony-containing material is chemically stable at ambient temperature, the antimony-containing material is represented by a non-carbon-containing chemical formula, and the adsorbent has a moisture-free environment with less than about 50 ppm moisture.

The objects and advantages of the present invention will be better understood from the following detailed description of its preferred embodiments, taken in conjunction with the accompanying drawings, in which like numbers indicate like features throughout.

1 illustrates a beamline ion implantation system incorporating principles of the present invention;

1 illustrates a plasma immersion ion implantation system incorporating principles of the present invention;

1 illustrates an exemplary storage and delivery container incorporating principles of the present invention;

Figure 3 shows an alternative storage and delivery container incorporating principles of the present invention;

The relationship and function of the various elements of this invention are better understood with the following Detailed Description. The Detailed Description contemplates various permutations and combinations of features, aspects, and embodiments within the scope of the disclosure. Accordingly, the present disclosure may consist of, or consist of, any such combinations and permutations of these specific features, aspects, and embodiments, as well as selected one or more thereof. or to consist essentially of them.

The invention may include any of the following embodiments in various combinations, and any other aspects described below in the written description or accompanying drawings. As used herein, the term "embodiment" means an embodiment that serves to illustrate by way of example and not limitation.

As used herein and throughout, the terms "Sb-containing ions" or "Sb ions" refer to Sb ions or Sb-containing ions, such as Sb ⁺ or Sb ²⁺ , which are suitable for implantation into a substrate; and Sb ₂ ⁺ and various Sb ion species, including oligomeric ions such as, but not limited to, Sb 2 +.

"Substrate," as used herein and throughout, is formed from any suitable material, including silicon, silicon dioxide, germanium, gallium arsenide, and alloys thereof, and contains other materials such as dopant ions. Any material, including but not limited to wafers or other sliced or non-sliced materials requiring ion implantation, such as implanted material, or similar target objects .

It should be understood that "Sb" and "antimony" are used interchangeably herein and throughout and are intended to have the same meaning. Reference to "Sb-containing material" or "Sb-containing source material" is intended to refer to the liquid phase of the antimony material of the present invention and the corresponding vapor phase in which the liquid phase is substantially in equilibrium. "Sb-containing liquid source material" is intended to mean a material of the invention that is substantially in equilibrium with its corresponding gas phase.

As used herein and throughout, the terms "vessel" and "container" are used interchangeably and are suitable for filling, storing, transporting and/or delivering materials. , dewars, bottles, tanks, barrels, bulk and microbulk, are intended to mean any type of storage, filling, transport and/or delivery container.

As used herein and throughout, all concentrations are expressed as volume percentages (“vol %”) unless otherwise indicated.

"Reduce," "reduced," or "reduction," as used herein and throughout, refers to an ion implantation process and (i) an adverse event or shortening, suppressing, and/or delaying the onset of adverse effects (e.g., reducing decomposition reactions, reducing ion short-circuiting), or (ii) reducing amounts to unacceptable levels where specific objectives cannot be achieved. (e.g., a reduced flow that cannot sustain the plasma), or (iii) to a non-substantial amount that does not adversely affect the particular purpose (e.g., destabilizing the flow to the arc chamber). or (iv) reduced by a significant amount compared to conventional practice but not altering the intended function (e.g., recondensing the material along the conduit). the gas phase of the material, while still maintaining the vapor phase of the material).

As used herein and throughout, when referring to a measurable value such as amount or duration over time, "about" or "approximately" refers to the specified value, as such variations are appropriate. ±20%, ±10%, ±5%, ±1% and ±0.1% variation from .

Throughout this disclosure, various aspects of this invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as limiting the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as all of the individual numerical values within that range. For example, a description of a range such as 1 to 6 refers to specifically disclosed subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, as well as It should be considered to have individual numbers within the range, such as 1, 2, 2.7, 3, 4, 5, 5.3, 6, and any whole and partial increments therebetween. . This applies regardless of the breadth of the range.

It is in view of the lack of suitable Sb source materials for ion implantation that the present invention emerges. The present disclosure, in one aspect, relates to compositions for antimony suitable for ion implantation as an n-type dopant and includes the following attributes. (i) an antimony-containing material capable of being stored in the liquid phase under sub-atmospheric conditions, the storage conditions being characterized herein by the absence of traces of moisture defined as about 50 ppm or less; (ii) the antimony-containing material is represented by a non-carbon-containing chemical formula; and (iii) the liquid phase of the antimony-containing material is substantially in the vapor phase in response to downstream vacuum pressure conditions. It is in substantial equilibrium with the corresponding gas phase, which can flow at a continuous flow rate.

The Sb-containing source material has a liquid phase that is substantially in equilibrium with the corresponding gas phase under storage conditions. The material remains stable at ambient temperature and does not tend to decompose during ion implantation use. Sb-containing materials as liquids have a suitable vapor pressure, which is defined herein as the amount of vapor capable of sustaining a flow rate of about 0.1-100 sccm into the arc chamber. . In particular, the flow rate of Sb-containing material in the gas phase is sufficient to generate and maintain a stable plasma during operation of the ion implanter. A stable plasma makes it possible to carry out the implantation of Sb ions at an arc voltage of about 50-150 V and an extraction voltage on the extraction electrode of about 1-300 keV, thereby producing a beam of Sb-containing ions. . The beam current for Sb-containing ions ranges from about 10 microamps to 100 mA, resulting in an Sb ion dose into the substrate of about 1E11-1E16 atoms/cm ² .

In one aspect, the Sb-containing source material of the present invention is stored in a container in a liquid phase that is substantially in equilibrium with its gas phase, which occupies the headspace of the container. The vapor phase of the Sb-containing source material can be recovered from the vessel and delivered along a conduit into the arc chamber of the ion implanter at ambient temperature conditions. Advantageously, and in contrast to conventional Sb-containing materials, the liquid phase Sb-containing source material replenishes (i) the headspace of the vessel and (ii) the conduit extending from the vessel to the arc chamber. has an evaporation rate that allows In this manner, a sufficient amount of the Sb-containing source material is evaporated into the gas phase to maintain a flow rate of about 0.1-100 sccm flowing into the arc chamber.

Applicants have discovered that it is necessary to maintain the evaporation rate of the liquid Sb-containing source material to produce a vapor phase flow rate of at least about 0.1 sccm or greater along the conduit into the arc chamber. . If the evaporation rate of the Sb-containing source liquid is less than or drops below a certain threshold, this results in a resulting flow rate of the Sb-containing source material in the gas phase of less than or equal to less than about 0.1 sccm. Down, the Sb-bearing material in the vapor phase can flow along the conduit into the arc chamber at a rate faster than the evaporation rate of the Sb-bearing source material contained within the vessel. The flow into the arc chamber can become unsustainable and eventually tends to reduce to unacceptably low levels or become erratic. Ultimately, in worst-case scenarios, the flow may stop completely or be reduced to such an extent that the ion beam becomes unstable and fails, requiring an interruption of the entire implantation process. becomes.

In an alternative embodiment, and as one possible means to accelerate the evaporation rate, the liquid source Sb-containing material is stored in a storage and delivery vessel maintained under sub-atmospheric conditions and subjected to an arc. The liquid source material evaporates at a relatively high rate sufficient to form the required amount of source material into the gas phase causing the required flow rate into the chamber of about 0.1-100 sccm. It may be possible to Therefore, the liquid source Sb-containing material evaporates into the gas phase at a sufficient rate to replenish the vapor in the headspace of the storage and delivery vessel and along the conduit extending into the arc chamber. to replenish the vapor, thereby generating and maintaining a gas phase flow rate of the Sb-containing source material between about 0.1 and 100 sccm during operation of the ion implanter for ion implantation.

In order to allow the necessary storage conditions for vaporization to occur, the storage and delivery vessel is configured to allow the necessary vapor phase to flow into the conduit extending to the arc chamber. It is configured with sufficient headspace in which a sufficient volume of vapor of the Sb-containing source can reside. Specifically, the storage and delivery container is configured to provide a liquid to headspace volume ratio of at least about 1:1, more preferably about 1:2, and most preferably about 1:3. In addition, preferably sufficient surface area of the Sb-containing liquid exposed to the gas phase within the storage and delivery vessel is used to allow the corresponding gas phase of the Sb-containing material to flow along the conduits to produce the Sb-containing vapor. Allowing the necessary evaporation to replenish the headspace of the storage and delivery vessels as it produces a substantially steady flow along the conduit and into the arc chamber. Specifically, the liquid surface area exposed to the gas phase is preferably at least 16 cm ² , more preferably about 50 cm ² or more, and most preferably greater than about 100 cm ² .

Other storage conditions for Sb-containing source materials can cause unacceptably low evaporation rates of liquid source materials. For example, if the Sb-containing liquid source material is stored in the storage and delivery container at pressures above atmospheric pressure, it can then be inadvertently introduced into the headspace of the storage and delivery container during the filling operation. The gas phase partial pressure of the liquid source material may be insufficient as a result of air, N ₂ , or any other inert and/or reactive gas species introduced into the liquid source material. Additionally, in such scenarios, contamination of the Sb-containing material in the gas phase by other contaminants would render the material unsuitable for use in the ion implantation process, which is generally associated with atmospheric pollution. The introduction of contaminants, including substances, into the arc chamber cannot be tolerated.

In another embodiment, the present invention provides for the Sb loading into the arc chamber by causing the gas phase of the Sb-containing material to flow from the vessel in substantially monomeric form with the elimination of oligomers or a reduced amount thereof. The purpose is to ensure the stability of the gas phase flow of the material. For example, the storage and delivery container reduces the number of oligomers (e.g., dimers, trimers, tetramers, and/or pentamers) formed within the gas phase, thereby substantially One possible means for forming a gas phase of a monomeric Sb-containing material can be heating to 65° C. or less. In another embodiment, the storage and delivery vessel may be heated to 50° C. or less as a means to form a gas phase of the substantially monomeric Sb-containing material. In yet another embodiment, the storage and delivery vessel can be heated to 40° C. or less as a means of forming a vapor phase of the substantially monomeric Sb-containing material. Applicants have found that under the same storage conditions, oligomers of gas phase Sb-containing materials can have flow rates substantially lower than those of monomeric gas phase Sb-containing materials, resulting in unacceptable flow instabilities and Recognize that it brings change. Thus, the selection of specific sub-atmospheric pressure and elevated temperature conditions, combined with vessel configurations suitable for sufficient vaporization as described above, can reduce the amount of oligomers in the vapor phase.

In another embodiment, the Sb-containing source material is co-flowed or sequentially flowed with an inert gas such as _N2 , He, Ne, Ar, Kr, or Xe to vaporize the Sb-containing source material into the arc chamber. Phase flow stability can be improved. Alternatively, or in addition, an inert gas may be configured to flow through the liquid phase Sb-containing source material or interact with the storage and delivery vessel.

In another aspect, the Sb-containing source material is stored in a storage and delivery container that is a moisture-free environment containing no traces of moisture, defined herein and throughout as less than or equal to about 50 ppm. In the presence of moisture, _halogenated Sb-containing compounds can react to form _Sb2O3 , _H2 , HF, or HCl. Such a moisture-free environment, containing no traces of moisture, can be achieved within the storage container by several techniques, one of which involves performing a so-called "freeze degassing" cycle. include. In one cycle of the freeze degassing process, the Sb-containing source material is cooled such that all of the vapor of the Sb-containing source material condenses out of the gas phase, while other contaminants such as moisture and nitrogen are Remain in the gas phase. After allowing sufficient time for the Sb-containing source material to condense, the headspace of the vessel is evacuated using a pump while substantially all vapor contaminants are removed leaving the Sb-containing material. The container continues to be cooled such that the remains in the container as a solid, liquid, or mixture thereof. When the contaminants have been removed, the vessel is sealed and the Sb-containing material, in solid, liquid, or mixture thereof, is heated to ambient temperature to form a liquid that is substantially in equilibrium with its corresponding phase. do. In this way, it is avoided that moisture and other impurities, especially atmospheric impurities, are introduced into the storage and delivery container. Other techniques for achieving a moisture-free environment for the Sb-containing material may be used, including but not limited to fluorine passivation of the inner surface of the container. Alternatively, a plastic container may be used to store and deliver the Sb-containing material to the arc chamber for ion implantation.

Detrimental effects of carbon-based deposits during Sb ion implantation are preferably avoided by the present invention. Sb-containing source materials are molecules represented by non-carbon-containing chemical formulas to reduce or eliminate the formation of carbon-based deposits within the arc chamber and throughout other areas of the ion source. Examples of carbon-based deposits include, but are not limited to, C, CF and CCl compounds. Carbon-based deposits can reduce ion source life by forming whiskers or other deposits of various shapes along various components of the ion implanter, including the extraction plate. can cause distortion of the shape of the ion beam. Alternatively, or in addition, carbon-based deposits can deposit and accumulate as residual particles on the substrate. The presence of carbon in the plasma can also reduce the Sb beam current due to the formation of carbon-containing ions that become freely available for plasma dilution. Accordingly, the present invention preferably utilizes Sb-containing source materials represented by non-carbon-containing formulas. In this way, avoidance of carbon in the Sb-containing source material reduces or eliminates the introduction of carbon-derived deposits entering the arc chamber with associated detrimental effects.

In a preferred embodiment, antimony pentafluoride (SbF ₅ ) is the Sb-containing source material for performing ion implantation. _SbF5 is a relatively strong Lewis acid etchant and can react violently with _moisture to produce _Sb2O3 and HF. Thus, the SbF5 source material is stored in a storage and delivery vessel under sub-atmospheric conditions, which is a moisture-free environment containing no traces of moisture, defined herein and throughout to be less than or equal to about 50 ppm. . SbF ₅ can be maintained as a liquid at about 25 degrees Celsius with a vapor pressure of about 10 Torr in a storage and delivery vessel operably connected to the arc chamber.

Other source materials are envisioned. For example, in another embodiment of the invention, SbCl ₅ is a suitable antimony-containing source material for ion implantation. SbCl ₅ can be maintained as a liquid at about 25 degrees Celsius with a vapor pressure of 7.6 Torr in a storage delivery vessel operably connected to the arc chamber. Other source materials according to the applicable criteria of the invention may also be used as described herein.

Despite the stability of _SbF5 and the process effects of using liquid-based materials for Sb ion implantation, the inventors have encountered one of the design challenges of utilizing SbF5 and other fluorine-containing Sb compounds: , recognized that the presence of fluorine in the compound can lead to excess fluorine ions in the plasma. Fluorine ions can propagate the so-called "halogen cycle", where excess halogen ions generally cause corrosion of the tungsten chamber walls onto the cathode, producing tungsten fluoride species represented by WFx. which can move onto the hot source filament which can deposit tungsten. Tungsten deposition tends to increase the operating voltage of the ion source, which in turn increases W deposition on the source filament until the source can eventually degrade. This halogen cycle tends to reduce the lifetime of the ion source.

Incorporating hydrogen-containing compounds during the use of any of the SbF5 or other Sb-containing source materials contemplated by this invention, particularly those containing fluorine atoms or other halogens, to mitigate the effects of the halogen cycle. be able to. Hydrogen-containing compounds are introduced into the arc chamber by any possible method, including sequential or co-flowing of the hydrogen-containing compounds with the SbF5 or other Sb-containing source material of the present invention. can be done. Alternatively, the hydrogen-containing compound can be stored as a mixture with SbF5 or other Sb-containing source materials contemplated by this invention. Suitable hydrogen- _containing compounds include _H2 , _CH3F , _CH2F2 , _Si2H6 , PH3, _{AsH3 , SiH4} , _{GeH4 , B2H6} , _CH4 , _NH3 , _or H ₂ S, and any combination thereof.

The amount of hydrogen-containing compound introduced into the arc chamber to reduce the halogen cycle can neutralize or eliminate the detrimental effects of fluorine or other halogens that may be contained in the Sb-containing source materials of the present invention. It should be as effective an amount as possible. When utilizing SbF5, the effective amount of the hydrogen-containing compound is preferably the total composition of SbF5 and the hydrogen-containing compound to provide a sufficient amount of hydrogen atoms to mitigate the detrimental effects of the halogen cycle. is at least about 20% by volume of the The term "effective amount," as used herein and throughout, refers to fluorine or other means the required amount of a particular material, such as a hydrogen-containing compound, to achieve a given goal, such as neutralization or elimination of the detrimental effects of halogen ions of . In one example, the volume percent of hydrogen-containing compound required to mitigate the halogen cycle can be about 50 volume percent of the resulting compositional mixture of SbF5 and hydrogen-containing compound formed in the arc chamber. . It should be understood that an effective amount of hydrogen-containing compound can be greater than about 50% by volume of the total composition of SbF5 and hydrogen-containing compound.

The avoidance of solid Sb-containing sources in the present invention by using the contemplated liquid source materials of the present invention that meet the applicable criteria defined herein involves several process effects. For example, when using the Sb-containing source materials of the present invention, typically a Reduce or avoid altogether the excessive heating required. At a minimum, conventional Sb-containing solids sources heat the conduit extending between the storage and delivery vessel and the arc chamber, causing condensation of the vaporizing but condensation-sensitive Sb-containing solids source during ion implantation. It is necessary to prevent In contrast, the present invention reduces the amount or eliminates the need to heat trace the conduit. The present invention also reduces or eliminates the risk of Sb-containing materials of the present invention depositing and accumulating on chamber walls and/or ion source filaments. Avoiding such excessive temperature increases also reduces or eliminates the tendency for decomposition and side reactions that can make the Sb ion implantation process difficult to control.

Additionally, the need for higher temperatures with other Sb sources, particularly Sb-containing solid sources, limits the use of control valves, thereby making flow regulation difficult. In the present invention, avoidance of high temperatures allows control valves to be used to control vapor flow at the desired rate referred to herein, resulting in stable and controlled operation of the ion implanter. enable In one embodiment, the controlled flow rate of the present invention operates the implanter at a beam current of at least about 10 microamps for an ion source lifetime of at least about 50 hours, while at about 1 glitch/minute. Allows to receive glitch speeds less than

Additionally, the present invention reduces or eliminates the need for carrier or reactant gases. In contrast, previously, as an example, a solid Sb-containing source was plated on a surface in close proximity to the arc chamber, thereby requiring elevated heating of the surface to evaporate the solid Sb-containing source. In some cases, carrier gases or reactive gases have been supplied. A carrier gas or reactive gas then directs the vaporized Sb-containing source into the arc chamber.

Referring to FIG. 1, a representative beamline ion implanter in accordance with the principles of the present invention is shown. Beam-line ion implantation systems are used to perform ion implantation processes. The components of a beamline ion implantation system are shown in FIG. The Sb-containing liquid source material 101 is selected in accordance with the principles of the present invention to have a suitable vapor pressure. Sb-containing source material 101 is stored in a storage and delivery vessel located within gas box 100, as shown in FIG. The Sb-containing liquid source material 101 is stored in a moisture-free environment containing no traces of moisture, defined herein as less than or equal to about 50 ppm. The Sb-containing liquid source material 101 is further represented by a non-carbon-containing formula. In a preferred embodiment, the Sb-containing liquid source material 101 is SbF5. Alternatively, the Sb-containing liquid source material 101 is SbCl5. One or more hydrogen-containing compounds may optionally be included in gas box 100 and mitigate the effects of the halogen cycle when Sb-containing materials containing halogens (e.g., SbF5 or SbCl5) are utilized. may flow into the arc chamber 103 in an effective amount for this purpose.

The Sb-containing liquid source material 101 is stored in a liquid phase that is substantially in equilibrium with the corresponding gas phase that occupies the headspace of the storage and delivery vessel. The vapor pressure of the Sb-containing source material 101 is sufficient to reduce or eliminate the amount of heating in the line between the gas box 100 and the ion source chamber 103, thereby allowing control stability of the above process. do. The gas phase of the Sb-containing liquid material 101 is configured to flow substantially continuously and at a suitable flow rate within the gas phase depending on the vacuum conditions downstream of the gas box 100 . Vapor exits the headspace of the storage and delivery container and flows into the conduit and therealong to the ion source chamber 103 . The vapor pressure of the Sb-containing source material in the storage and delivery vessels in the gas box 100 is sufficient to allow a steady gas phase flow of the Sb-containing source material into the arc chamber 103 along the conduit. . The vapor phase of Sb-containing liquid material 101 is introduced into ion source chamber 103 and ionization of material 101 occurs. Energy is introduced into chamber 103 to ionize the Sb-containing vapor. A flow controller 102, which may include one or more mass flow controllers and corresponding valves, is used to control the gas phase flow rate at a predetermined value. Excessive temperatures, such as typically required in conventional solid-containing Sb sources, are avoided in the process of FIG. 1, thereby controlling vapor flow at the desired flow rates referred to herein. This allows the use of control valves to allow stable and controlled operation of the ion implanter. Ionization of Sb-containing materials can produce various antimony ions. An ion beam extraction system 104 is used to extract antimony ions from the ion source chamber 103 in the form of an ion beam of desired energy. Extraction can be performed by applying a high voltage across the extraction electrodes. Carry the beam through a mass analyzer/filter 105 to select the Sb ion species to be implanted. The ion beam is then accelerated/decelerated 106 and transported to the surface of a target workpiece 108 (ie, substrate) positioned at an end station 107 for implanting ions into the workpiece 108 . obtain. The workpiece can be, for example, a semiconductor wafer or similar target object requiring ion implantation. The Sb ions of the beam impinge on the surface of the workpiece and penetrate to a specific depth to form a doped region with desired electrical and physical properties.

It should be understood that the novel Sb-containing materials of the present invention can be utilized with other ion implantation systems. For example, as shown in FIG. 2, a plasma immersion ion implantation (PIII) system may also be utilized to implant Sb ions. Such a system includes a gas box 200 that is similar in construction to beamline ion implanter 100 . Operation of the PIII system is similar to operation of the beamline ion implantation system of FIG. Referring to FIG. 2, the vapor phase of the Sb-containing liquid source material of the present invention is introduced from source 201 into plasma chamber 203 by flow controller 202 . Source 201 represents a storage and delivery vessel configured to store a liquid phase of Sb-containing material in substantial equilibrium with a corresponding gas phase occupying the headspace of the storage and delivery vessel. The Sb-containing liquid source material 201 is stored in a moisture-free environment containing no traces of moisture, defined herein as less than or equal to about 50 ppm. The Sb-containing liquid source material 101 is further represented by a non-carbon-containing formula. In a preferred embodiment, the Sb-containing source material 101 is SbF5. Alternatively, the Sb-containing source material 101 is SbCl5.

The vapor pressure of the Sb-containing source material 201 is sufficient to reduce or eliminate the amount of heating in the line between gas box 200 and plasma chamber 203, thereby allowing control stability of the above process. . The gas phase of the Sb-containing liquid source material 201 is configured to flow substantially continuously and at a suitable flow rate within the gas phase depending on the vacuum conditions downstream of the gas box 200 . The gas phase exits the headspace of the storage and delivery vessel and flows into the conduit and therealong to the plasma chamber 203 . The vapor pressure of the Sb-containing source material within the storage and delivery vessels in the gas box 200 is sufficient to allow a steady gas phase flow of the Sb-containing source material into the arc chamber 203 along the conduit. . As the vapor phase of the Sb-containing liquid material is introduced into the ion source chamber 203, energy is subsequently provided to ionize the Sb-containing vapor and produce Sb ions. Sb ions present in the plasma are accelerated toward the target workpiece 204 . One or more hydrogen-containing compounds may optionally be included in gas box 200 and mitigate the effects of the halogen cycle when Sb-containing materials containing halogens (e.g., SbF5 or SbCl5) are utilized. It should be understood that it may flow into the plasma chamber 203 in an effective amount for this purpose.

In another aspect of the invention, a storage and delivery container for the Sb-containing source material disclosed herein is provided as shown in FIG. This storage and delivery container allows safe packaging and delivery of the Sb-containing source material of the present invention. The Sb-containing source material of the present invention is contained within container 300 . Vessel 300 includes an inlet port 310 to allow filling of vessel 300 with a desired Sb-containing source material. This port can also be used to purge the interior of vessel 300 with an inert gas and to evacuate vessel 300 prior to filling the desired Sb dopant material. In one example, a freeze-pump-thaw cycle can be performed utilizing the container 300 to create a moisture-free environment that does not contain traces of moisture of about 50 ppm or less.

An exit port 320 is provided for withdrawing the gas phase of the Sb-containing material from the headspace of vessel 300 . A vacuum-operated check valve 330 is provided upstream of the outlet port to dispense a controlled flow of Sb-containing material in response to sub-atmospheric conditions occurring downstream of cylinder 300 . The present vacuum-operated check valve 330 enhances safety while handling the various Sb-containing materials of the present invention. When valve 321 is open to atmospheric pressure, check valve 330 prevents the introduction of any air or other contaminants within vessel 300, thus allowing gas phase Sb to occupy the headspace of vessel 300. It reduces both the contamination risk and the partial pressure reduction of the contained material. In this way, a high purity level of the Sb-containing material can be maintained in a safe manner during its storage, delivery and use, thereby allowing the recovery of the Sb-containing source material during ion implantation. The gas phase can maintain the proper vapor pressure to generate the required flow rate. Check valve 330 may be located outside container 300 (Case I). Alternatively, check valve 330 may be located inside container 300 (Case II). Vessel 300 is in fluid communication with the exhaust flow path, and check valve 330 is responsive to sub-atmospheric pressure conditions established along the exhaust path to remove Sb-containing source material from the interior volume of vessel 300. operates to allow a controlled flow of

Vessel 300 may be a cylinder for holding the Sb-containing material in at least a partial gas phase under sub-atmospheric conditions. The Sb-containing material is stored under sub-atmospheric conditions therein. The Sb-containing material remains chemically stable and does not undergo decomposition within the cylinder 300 interior. The Sb-containing material is preferably stored as a liquid at ambient temperature (20-25°C). In one embodiment, the vapor pressure is greater than about 1 Torr. In another embodiment, the vapor pressure is greater than about 3 Torr, and more preferably greater than about 5 Torr.

Cylinder 300 preferably includes a dual port valve assembly in mechanical communication with cylinder 300 . A dual port valve is shown in FIG. 4 and comprises an injection port valve and an exhaust port valve, the injection port valve being in fluid communication with the interior of the cylinder for introducing the Sb-containing dopant material therein. The exhaust port valve is in fluid communication with a flow exhaust path extending from the interior of the cylinder to the exterior to exhaust the antimony-containing dopant material therefrom. A check valve 330 is disposed along the flow exhaust path, the check valve configured to move from a closed position to an open position in response to sub-atmospheric conditions outside the cylinder.

Other storage containers are envisioned. For example, in an alternative embodiment, an antimony-containing dopant material may be stored and dispensed from an adsorbent-based delivery system. A variety of suitable adsorbents are contemplated, including but not limited to carbon-based adsorbents or metal-organic frameworks.

In yet another embodiment, commercially available from Praxair (Danbury, Conn.), U.S. Patent Nos. 5,937,895; 6,045,115; , 708,028, and 7,905,247, and U.S. Patent Publication No. 2016/0258537, all of which are incorporated herein by reference in their entirety. ™ delivery device may be used herein to safely deliver a controlled flow rate of the gas phase of the Sb-containing source material from the vessel 300 to the ion device for Sb ion implantation. The vacuum actuated check valve of the UpTime® delivery device prevents air and other gas contamination at atmospheric pressure that may be present in the ambient environment from seeping into the container and contaminating the Sb-containing precursor material; It serves to prevent the partial pressure from decreasing.

Other suitable sub-atmospheric delivery devices may include pressure regulators, check valves, excess flow valves, and flow restriction orifices in various arrangements. For example, two pressure regulators can be placed in series in the cylinder to allow the cylinder pressure of the Sb-bearing source material in the gas phase within the vessel to a downstream mass flow controller housed along the fluid discharge line. may be adjusted downward to a predetermined pressure.

Vessel or cylinder 300, along with its contemplated variations, may be configured in combination with a beam-line ion implantation system (FIG. 1), whereby vessel or cylinder 300 may be configured with flow lines or conduits extending therebetween. A network is operably connected to the system. Advantageously, the conduit is preferably characterized by an eliminated or reduced amount of heat tracing compared to conventional Sb-containing sources.

Alternatively, the vessel or cylinder 300, along with its contemplated variations, may be configured in combination with a plasma immersion injection system (FIG. 2), whereby the vessel or cylinder 300 is configured with flow lines or conduits extending therebetween. A network is operably connected to the plasma immersion system. Advantageously, the conduit is preferably characterized by an eliminated or reduced amount of heat tracing compared to conventional Sb-containing sources.

A number of advantages of the present invention are envisioned. Utilization of the liquid-based Sb-containing precursors of the present invention for delivery of a Sb-containing gas phase, for example for Sb ion implantation, followed by switching to a different gaseous dopant source is generally used for Sb ion implantation. Less time is required compared to using a solid-based Sb-containing precursor for . Specifically, utilization of the liquid-based Sb-containing precursors of the present invention for delivery of Sb-containing gas phases compared to solid Sb-containing sources is required to switch to different dopant species for ion implantation. reduces the required start-up time, thereby resulting in greater wafer throughput for the implanter. As an example, an implanter running solid arsenic (As) or solid phosphorous (P) as the source material for implanting the respective ion species is expected to require about 30 minutes to adjust the ion beam. On the other hand, use of gaseous _AsH3 or gaseous _PH3 source materials can generally be expected to require only about 4 minutes to adjust the ion beam. As used herein and throughout, the terms "conditioning" or "conditioning" refer to the process of producing a beam of only target ion species with a particular beam current and size. By comparison, for solid Sb-containing source materials, the mass flow rate into the arc chamber is controlled by the vaporizer temperature required for sublimation, and the Sb-containing source requires that the solid source be converted to the gas phase prior to delivery to the arc chamber. and stored to ensure that it is sufficiently heated. Considering the time to heat the solid Sb-containing source material to its gas phase, the time to condition the beam, and then the time to cool down the solid Sb-containing source upon completion of the ion implantation process, it is possible to switch to another dopant species. A total time of about 30-90 minutes can occur, while delivery of a gaseous dopant source derived from a Sb-containing liquid precursor can require a duration of about 5-10 minutes. The net result can be a significant increase in throughput with the present invention.

Additionally, the liquid-based Sb-containing precursors of the present invention can be placed in the same gas box (e.g., as shown in Figures 1 and 2) with other dopant sources without the need for additional heating. can. In contrast, Sb-containing solid sources require a separate evaporator positioned along a conduit extending into the arc chamber for the purpose of ensuring that the Sb-containing vapor does not recondense, which requires more space than may be available and further adds complexity and cost to the ion implantation process.

As can be seen, the present invention is useful for ion implantation, including Sb-containing solid sources, which are difficult to consistently deliver into arc chambers due to their low vapor pressure and limited thermal stability. , provides a feasible solution for conventional Sb-containing sources.

While what is considered to be specific embodiments of the invention have been shown and described, it will be appreciated that various modifications and changes in form or detail can readily be made without departing from the spirit and scope of the invention. will be understood. Accordingly, the present invention is not limited to the precise forms and details shown and described herein, but any less than the full scope of the invention disclosed and hereinafter claimed. is also intended to be non-limiting.
The following are further disclosed in relation to the present invention.
[1]
A composition suitable for ion implantation to implant antimony-containing ions to produce an n-type electronic device structure, comprising:
An antimony-containing material, wherein said antimony-containing material is chemically stable at ambient temperature and maintained under sub-atmospheric pressure, liquid phase storage conditions, and wherein said storage conditions are comprising an antimony-containing material characterized by a lack of moisture of
The antimony-containing material is represented by a non-carbon-containing chemical formula,
A composition wherein said antimony-containing material in said liquid phase is in a liquid phase in substantial equilibrium with a corresponding gas phase adapted to exert sufficient vapor pressure in response to downstream vacuum pressure conditions. .
[2]
The composition according to [1], further comprising a hydrogen-containing compound, wherein the hydrogen-containing compound is in an effective amount for reducing halogen cycle.
[3]
The composition according to [1], wherein the antimony-containing material is SbF5 _.
[4]
The composition of [1], wherein the Sb-containing dopant material has a water content of about 50 ppm or less.
[5]
The composition of [1], wherein the Sb-containing material is SbF5, and the SbF5 is maintained as a liquid at about 25 degrees Celsius with a vapor pressure of about 10 _{Torr .}
[6]
A subatmospheric storage and delivery vessel for a composition suitable for ion implantation to implant antimony ions to produce an n-type electronic device structure, comprising:
an antimony-containing material, said antimony-containing material being chemically stable at ambient temperature;
The antimony-containing material is represented by a non-carbon-containing chemical formula,
A storage and delivery container defined at least in part by a moisture-free environment characterized by the lack of said trace amount of moisture, said storage and delivery container being said antimony-containing material in a liquid phase under sub-atmospheric conditions. so that said liquid phase is in substantial equilibrium with a corresponding gaseous phase occupying the headspace of said storage and delivery container. Pneumatic storage and delivery container.
[7]
A dual port valve assembly in mechanical communication with the storage and delivery container, the dual port valve comprising an inlet port valve and an outlet port valve, the inlet port valve having therein the In fluid communication with the interior of the storage and delivery container for introducing an antimony-containing material, the discharge port valve in fluid communication with a flow discharge path extending from the interior to the exterior of the storage and delivery container. and exhausting said corresponding vapor phase of said antimony-containing material therefrom.
[8]
The sub-atmospheric storage and delivery container of [1], wherein the antimony-containing material is stored as a liquid at about 20-25°C with a vapor pressure of about 760 Torr or less.
[9]
A check valve is further included along the flow discharge path, and the storage and delivery vessel is responsive to a downstream pressure of about 760 Torr or less to release the corresponding vapor phase of the antimony-containing material to the storage and delivery vessel. The subatmospheric storage and delivery container of [6], configured to dispense from the headspace of the delivery container.
[10]
Sub-atmospheric pressure according to [6], further comprising a hydrogen-containing compound mixed with said antimony-containing material as part of a single source or stored in a separate container as part of a kit. Storage and Delivery Containers.
[11]
A method of operating an ion source for implanting Sb-containing ions comprising:
introducing a vapor phase antimony-containing material into the arc chamber at a flow rate of at least about 0.1 sccm or greater;
ionizing the composition to produce Sb-containing ions within the arc chamber;
and implanting said Sb-containing ions into a substrate.
[12]
12. The method of claim 11, wherein the glitch rate is about 1 glitch per minute or less over an ion source lifetime of about 50 hours.
[13]
The method of [11], further comprising introducing an effective amount of a hydrogen-containing compound into the arc chamber.
[14]
The method of [11], wherein the antimony-containing composition when stored in the vapor phase is provided to the arc chamber in the absence of heating of the vapor phase.
[15]
The method of [11], further comprising maintaining the evaporation rate of the antimony-containing composition during the method of operating the ion source to produce the gas phase at a flow rate of at least about 0.1 sccm or greater. the method of.
[16]
The method of [11], further comprising maintaining the temperature of the antimony-containing material in the gas phase not exceeding about 65 degrees Celsius.
[17]
The method of [11], further comprising operating the ion source at an arc voltage of about 50-150V.
[18]
An ion source apparatus configured to perform antimony-containing ion implantation at an arc voltage of less than about 150V, wherein said ion source is adapted to receive at least about 0.1 sccm of an antimony-containing composition in the vapor phase.
[19]
The ion source apparatus of [18], further comprising an average glitch rate of less than or equal to about 1 glitch per minute for a source lifetime of at least about 50 hours.
[20]
An adsorbent comprising a deliverable adsorption capacity for subatmospheric storage and delivery for a composition suitable for ion implantation to implant antimony ions to produce an n-type electronic device structure, said composition an article comprising an antimony-containing material, said antimony-containing material being chemically stable at ambient temperature;
The antimony-containing material is represented by a non-carbon-containing chemical formula,
An adsorbent, wherein the adsorbent has a moisture-free environment having a moisture content of about 50 ppm or less.

Claims (5)

A method of operating an ion source for implanting Sb-containing ions comprising:
introducing a vapor phase antimony-containing material into the arc chamber at a flow rate of at least 0.1 sccm or greater;
ionizing the composition to produce Sb-containing ions within the arc chamber;
implanting the Sb-containing ions into a substrate;
a glitch rate of less than or equal to 1 glitch per minute over a 50 hour ion source lifetime;
the antimony-containing composition when stored in the vapor phase is provided to the arc chamber in the absence of heating of the vapor phase;
producing a vapor phase antimony-containing material by evaporation from the liquid phase ;
the aforementioned method. 2. The method of claim 1, further comprising introducing an effective amount of a hydrogen-containing compound into said arc chamber. 2. The method of claim 1, further comprising maintaining an evaporation rate of the antimony-containing composition during the method of operating the ion source to produce the gas phase at a flow rate of at least 0.1 sccm or greater. Method. 2. The method of claim 1, further comprising maintaining a temperature of said antimony-containing material in said gas phase not exceeding 65 degrees Celsius . 2. The method of claim 1, further comprising operating the ion source at an arc voltage of 50-150V.

Images